1. Field of the Invention
This invention relates to a power window apparatus used for automatically raising and lowering a window glass of motor vehicles and a control method for the power window apparatus, and more particularly to improvement in the safety of the power window apparatus in a case of pinching a part of passenger's body such as a finger, a hand, an arm and so on between the window glass and the window frame.
2. Description of the Prior Art
In the conventional power window apparatus for automatically moving the window glass of the motor vehicle upwardly and downwardly, when the window switch is switched on toward the opening side in a manual mode, an electric current is supplied to the power window motor in the direction for lowering the window glass as long as the window switch is operated, and when the window switch is switched on toward the closing side in the manual mode, the electric current is supplied to the power window motor in the direction for raising the window glass as long as the window switch is operated.
The power window motor is provided with a rotation sensor, and the rotation sensor generates pulses according to the rotation of the motor shaft of the power window motor. The controller of the power window apparatus detects the present position of the window glass and load applied on the window glass on basis of the counting value and the pulse interval of the pulse signal generated from the rotation sensor.
If the pulse interval of the pulse signal generated from the rotation sensor becomes larger than a predetermined reference value and the counting value of the pulse signal indicates that the window glass is near to the full-closed position when the window glass is moving in the closing direction in response to the on-operation of the window switch on the closing side, the controller stops the window glass by cutting off the current supply to the power window motor according to the detection that the window glass reaches to the full-closed position. Additionally, if the pulse interval becomes larger than the reference value though the window glass does not reach at the full-closed position in this case, the controller detects that a finger, a hand of the passenger or the other thing is caught between the window glass and the window frame (hereinafter called as "pinching"), and returns the window glass in the opening direction from the closing direction by reversing the current direction supplied to the power window motor.
However, in the conventional power window apparatus having the aforementioned structure, it takes some time for detecting the pinching and returning the window glass in the opening direction. Therefore, if the window switch is switched off at the same time the finger or the like is caught by the window glass, namely before the controller detects the pinching and returns the window glass, the window glass stops at the state where the finger or the like is pinched between the window glass and the window frame. Accordingly, there is a problem since there is the possibility that the finger, the arm or the like pinched by the window glass may be injured.